CAIRO -- Egyptian President Mohammed Morsi offered nothing concrete to defuse the country's worst political crisis in nearly two years in a nationally televised speech late Thursday, refusing to rescind a disputed constitution drafted by his allies or his decrees giving him near absolute powers.

A night after thousands of his supporters and opponents fought pitched battles outside his Cairo palace that left at least six dead and nearly 700 injured, he angrily accused some of the opposition protesters of serving remnants of the old regime. He vowed never to tolerate anyone working for the overthrow of his "legitimate" government.

Some among the thousands of opposition protesters gathered near his palace raised their shoes in contempt as they listened to him. Others broke into the iconic Arab Spring chant of "the people want to topple the regime."

He also invited the opposition to a "comprehensive and productive" dialogue starting Saturday at his presidential palace, but offered no sign at all that he might offer any meaningful concessions.

The opposition has already stated that it would not enter a dialogue with Morsi unless he first rescinds decrees giving him nearly unrestricted powers and shelves the constitution draft hurriedly adopted by his Islamist allies.

Hamas chief to make first visit to Gaza Strip

GAZA CITY, Gaza Strip -- The supreme Hamas leader's first visit to the Gaza Strip this weekend signals growing regional acceptance of the Islamic militant movement in charge of the once isolated territory and grudging acquiescence by Israel.

Hamas chief Khaled Mashaal, who has positioned himself as a pragmatist and enjoys the backing of regional heavyweights Egypt, Turkey and Qatar, could also use the trip to lobby for re-election.

Mashaal is to arrive today for a three-day tour, with Hamas' 25th anniversary rally on Saturday set as the centerpiece. He'll visit the homes of two Hamas icons assassinated by Israel, military chief Ahmed Jabari and spiritual leader Sheik Ahmed Yassin.

His visit comes two weeks after the bloodiest round of Israel-Gaza fighting in four years, which included the killing of Jabari as well as hundreds of Israeli airstrikes on Hamas targets.